The aims of this research project are: (1) to determine the origin of fetal unsaturated fatty acids, (2) to describe the development of the fatty acid desaturase and elongation systems in the fetus and neonate, (3) to describe the effects of pregancy on maternal fatty acid desaturase and elongation, and (4) to determine the effects of maternal diabetes on the above three. This research will utilize both and in vitro studies on the synthesis and transport of unsaturated fatty acids, particularly essential fatty acids, in pregnant rats, guinea pigs and rabbits. The enzymes and proteins involved in the synthesis of these compounds will be assayed in homogenates and subcellulary fractions of maternal and fetal organs at various gestational ages and in the neonate. The in vivo transport of radioactive unsaturated fatty acids across the placenta will be measured. The effect of chemically induced diabetes on the maternal and fetal plasma levels of essentail fatty acids and the enzymic activities will be determined. The effects of human diabetes on the plasma levels of essential fatty acids in pregnant women and in the cord blood of their infants will be determined.